Charged heavy ions--carbon or other ions--appear to offer the combined advantages of high LET and superior dose localization in radiation therapy. The purpose of the design study carried on under this grant is to produce preliminary specifications, plans, and cost estimates of accelerators which could produce these beams and would be suitable for installation in a hospital. The accelerator would have to meet high standards or reliability, simplicity of operation and maintenance, and moderate operating costs. Full advantage of computer control would be taken to realize these objectives. While the primary purpose of the accelerator(s) will be radiation therapy, the capability for diagnostic imaging and production of radioisotopes will also be examined.